The present invention relates to an automatic immunoassay apparatus and a method of using the same.
Immunoassay is generally performed by using various label compounds such as enzymes, fluorescent substance such as fluorescein or rhodamine, luminous substance such as acridinium ester, luminol or isoluminol and a radioisotope such as .sup.125 I, .sup.131 I, .sup.14 C or .sup.3 H. Radio immunoassay using a radioactive isotope as a label compound (RIA) and enzyme immunoassay using an enzyme as a label compound (EIA) are well known. Among them, EIA has been utilized widely in particular in the field of clinical test in view of its specificity and sensitivity. In EIA, it is usual to attach an antigen or antibody selected for a specific object, i.e. antibody or antigen, to be measured to solid phase material and the solid phase material carrying the selected antigen or antibody is allowed to contact with the object contained in a sample solution to thereby cause an antigen-antibody reaction to occur therebetween. Enzyme labelling reacted or bound antigen or antibody is separated from non-reacted, i.e., free enzyme labelled antigen or antibody. After the separation which is usually called as Bind/Free (B/F) separation, the activity of enzyme labelling the reacted substance is measured, so that the measuring object in the sample is quantitatively measured.
Therefore, in order to perform EIA, a plurality of very complicated procedures, such as fractional addition of reagent, etc., dilution, agitation, B/F separation, solid phase shift, etc., are required.
Solid phase materials known to be used in EIA are polystyrene beads, magnetic particles, and the inner wall surface of a reaction chamber.
Some improvements on EIA have been proposed. One of them is directed to an improvement of a reagent container to be used in EIA. Japanese Kokai (P) 62-273453 discloses a technique for performing EIA with high sensitivity, in which magnetic particles are used as the solid phase material and the B/F separation is performed by using a special container containing such magnetic particles and a magnetic separating device having a permanent magnet configured correspondingly to the container. Further, Japanese Kokai (P) 1-201156 discloses a technique in which a microplate for containing magnetic particles and a magnetic separator are used. Japanese Kokai (P) 63-281053 discloses a container having a plurality of wells such as reaction well and sample wells, etc., arranged in a matrix.
On the other hand, a semi-automatic measuring device for measuring a large number of samples has been developed such as shown in E. Ishikawa, "Enzyme Immunoassay", Igaku Shoin, pages 180-207.
It has been known, however, that, in any of the known methods and apparatus, it takes 1 hour to 18 hours to perform the measurement manually even if such magnetic particle is used as the solid material. Even if the conventional semi-automatic device is used, this time can not be reduced sufficiently because some complicated procedures are still necessary as they are.